1/15
www.rohm.com 2010.10 - Rev.
A
© 2010 ROHM Co., Ltd. All rights reserved.
Sound Processors for BOOM BOX / Mini-component Stereo
Sound Processors
with Built-in 2-band Equalizers
BD3870FS,BD3871FS,BD3872FS,BD3873FS
●Description
The Sound Processor with built-in 2 Band Equalizer, incorporates functions required for BOOM BOX and mini-component
systems, such as input selector, input gain amp, volume, surround, tone (bass, treble), and loud speaker equalizer
(BD3872FS only). These functions can be controlled thro ugh the two-wire serial control.
●Features
1) Using external components, center frequencies and Q factors of the bass characteristics are flexible.
2) Providing a mute switch onto one of the input pins allows cross-talk suppression.
3) A surround function can be constructed without exter nal components.
4) Energy-saving design resultin g in low current consumption, by utilizing the BiCMOS proce ss
●Applications
BOOM BOX, mini-audio systems, and micro-audio system s.
●Line up matrix
Parameter BD3870FS BD3871FS BD3873FS BD3872FS
Input Gain 0, 6, 12, 18dB 24, 26, 28dB 18, 21, 24, 27dB 0, 5, 10, 19, 21,
23, 26, 28dB
Loud Speaker Equalizer (SEQ) No No No Yes
Input Selector Three inputs Three inputs Three inputs Five inputs
Volume 0 to -87dB/
1dB step, -dB 0 to -87dB/
1dB step, -dB 0 to –87dB/
1dB step, -dB 0 to -87dB/
1dB step, -dB
Equalizer 2 band
(Bass, T reble) 2 band
(Bass, T reble) 2 band
(Bass, T reble) 2 band
(Bass, T reble)
Surround Yes Yes Yes Yes
Serial Control Two-wire serial Two-wire serial Two-wire serial Two-wire serial
Package SSOP-A24 SSOP-A24 SSOP-A24 SSOP-A32
●Absolute maximum ratings (Ta=25℃)
Prameter Symbol Ratings Unit
BD3870FS BD3871FS BD3873FS BD3872FS
Power Supply Voltage Vcc 10 10 10 10 V
Power Dissipation Pd 800 *1 800 *1 800 *1 950 *2 mW
Operating Temperature Range Topr -25 to +75 -25 to +75 -25 to +75 -25 to +75 ℃
Storage Temperature Range Tstg -55 to +125 -55 to +125 -55 to +125 -55 to +125 ℃
*1 Reduce d by 8.0 mW/℃ at 25℃ or higher, when installed on the standard board (Size: 70×70×1.6mm).
*2 Reduce d by 9.5 mW/℃ at 25℃ or higher, when installed on the standard board (Size: 70×70×1.6mm).
●Operating voltage range
Prameter Symbol Ratings Unit
BD3870FS BD3871FS BD3873FS BD3872FS
Operating Voltage Range Vcc 4.5 to 9.5 4.5 to 9.5 4.5 to 9.5 4.5 to 9.5 V
*It must function normally at Ta=25℃.
No.10086EAT02
Technical Note
2/15
www.rohm.com 2010.10 - Rev.
A
© 2010 ROHM Co., Ltd. All rights reserved.
BD3870FS,BD3871FS,BD3872FS,BD3873FS
●Electrical characteristics
(Ta=25 ℃, VCC=8V, f=1kHz, Vi=200mVrms, RL=10kΩ, Rg=600Ω, Input Gain=0dB (BD3870FS, BD3872FS only),
Input Gain=24dB (BD3871FS only), Input Gain=18dB (BD3873FS only),Volume=0dB, Bass=0dB, Treble=0dB,
Surround=OFF, Loud Speaker Equalizer=OFF (BD3872FS only), unless other wise noted)
Block
Parameter Symbol Limits Unit Condition
Min. Typ. Max.
Total
Circuit Current IQ - 8 21 mA At no signal
Total Output Voltage Gain Gv
-2 0 2
dB
BD3870FS, BD3872FS
Gv=20log(VOUT/VIN)
22 24 26 BD3871FS
Gv=20log(VOUT/VIN)
16 18 20 BD3873FS
Gv=20log(VOUT/VIN)
Total Harmonic Distortion ratio THD - 0.01 0.1 % BW=400 to 30kHz
Maximum Output Voltage Vom 1.6 2.1 - Vrms THD=1%
BW=400 to 30kHz
Total Output Noise Voltage Vno - 4.5 15
µVrms
BD3870FS, BD3872FS
Rg=0Ω, BW=IHF-A
- 40 80 BD3871FS, BD3873FS
Rg=0Ω, BW=IHF-A
Total Residual Noise Voltage Vmno - 4.5 15 µVrms Rg=0Ω, BW=IHF-A
Volume=-dB
Cross-talk between Channels CTC - -80 -70 dB Rg=0Ω, BW=IHF-A
VOUT=1Vrms
Cross-talk between Selectors CTS - -80 -70 dB Rg=0Ω, BW=IHF-A
Input Impedance Rin 35 50 65 kΩ BD3870FS, BD3871FS, BD3 873FS
70 100 130 BD3872FS
Output Impedance Rout - - 50 Ω
Volume
Volume Control Range VRI -90 -87 -84 dB VR=20log(VOUT/VIN)
Maximum Volume Attenuation Vmin - - -90 dB BW=IHF-A
Volume Input Impedance Rvin 39 56 73 kΩ
Bass
Bass Boost Gain GBB 12 14 16 dB GB=20log(VOUT/VIN)
Bass Cut Gain GBC -16 -14 -12 dB GB=20log(VOUT/VIN)
Bass Step Resolution BR - 2 - dB
Treble
Treble Boost Gain GTB 10 12 14 dB BD3870FS, BD3871FS, BD3873FS
12 14 16 BD3872FS
Treble Cut Gain GTC -14 -12 -10 dB BD3870FS, BD38 71FS, BD3873FS
-16 -14 -12 BD3872FS
Treble Step Resolution TR - 2 - dB
Surround
Surround In-phase Gain Vsur1 -2 0 2 dB 2ch in-phase inputs
Surround Single-phase Gai n Vsur2 4.3 6.3 8.3 dB 1ch input, 1ch grounded
Surround Opposite-phase Gain Vsur3 8 10 12 dB 2ch opposite-phase inputs
SEQ
Loud Speaker Equa lizer Gain
(BD3872FS only) Seq 3 5 7 dB f=10kHz
* For measurement, VP-9690A (Average value wave detection, Effective value display) IHF-A filter by Matsushita Communication Industrial is used.
* Phase relation between Input/Output signal terminals is the same.
* Note: This IC is not designed to be radiation-resistant.
Technical Note
3/15
www.rohm.com 2010.10 - Rev.
A
© 2010 ROHM Co., Ltd. All rights reserved.
BD3870FS,BD3871FS,BD3872FS,BD3873FS
SC
(CLOCK)
thd thdth ts ts1 th1 tsd
twc
twh
twd tw1
tsu
DATA DATA
LATCH
90% 90% 90% 90%
10% 10% 10%
90% 90% 90% 90% 90%
10% 10% 10%
twc
End with Low
SI
DATA
LATCH
●Timing chart
1) Signal Timing Conditions
・Data is read on the rising edge of the clock.
・Latch is read out on the falling edge of the clock.
・Latch signal must end with the LOW state.
・To avoid malfunctions, clock and data signals must terminate with the LOW state.
1byte=10bit
Fig.1
Parameter Symbol Limits Unit
Min. Typ. Max.
Minimum Clock Width Twc 2.0 - - µs
Minimum Data Width twd 2.0 - - µs
Minimum Latch Width Tw1 2.0 - - µs
Data Set-up Time (DATACLK) Tsd 1.0 - - µs
Data Hold Time (CLKDATA) Thd 1.0 - - µs
Latch Set-up Time (CLKLATCH) Ts1 1.0 - - µs
Latch Hold Time (DATALATCH) Th1 1.0 - - µs
Latch Low Set-up Time Ts 1.0 - - µs
Latch Low Hold Width Twh 2.0 - - µs
2) Voltage Conditions for Control Signals
Parameter Limits Unit Condition
Min. Typ. Max.
(≦Vcc)
“H” Input Voltage 2.2 - 5.5 V Vcc=4.5 to 9.5V
“L” Input Voltage 0 - 1.0 V Vcc=4.5 to 9.5V
Technical Note
4/15
www.rohm.com 2010.10 - Rev.
A
© 2010 ROHM Co., Ltd. All rights reserved.
BD3870FS,BD3871FS,BD3872FS,BD3873FS
3) Control Data Format List
Basic Configuration of Control Data Format
Data input direction
MSB LSB
D9 D8 D7 D6 D5 D4 D3 D2 D1 D0
Data Select
Address
Control Data Format (BD3870FS, BD3871FS, BD3873FS)
Data input direction
D9 D8 D7 D6 D5 D4 D3 D2 D1 D0
(1) Input Selector Input Gain Surround * * * 0 0
(2) Volume A Volume B * 0 1
(3) Bass Gain Treble Gain 1 0
(4) * * * * * * * * 1 1
Control Data Format (BD3872FS)
Data input direction
D9 D8 D7 D6 D5 D4 D3 D2 D1 D0
(1) Input Gain Input Selector * * 0 0
(2) Volume A Volume B * 0 1
(3) Bass Gain Treble Gain 1 0
(4) * * * * * * Surround SEQ 1 1
・”*” indicates 0 or 1.
・By changing the setting of Select Address, three or four different control formats (BD3871FS, BD3872FS,
BD3873FS, plus BD3872FS) are selectable.
・In every power-on sequence, all of the address data must be initialized.
Example:
←Input direction
MSB LSB MSB LSB MSB LSB MSB LSB
Data(1) L Data(2) L Data(3) L Data(4) L
“L” indicates a latch.
・After power-on, for the second and subsequent times, only the necessary data can be selected for setting.
Example: When changing the volume,
←Input direction
MSB LSB
Data(2) L
“L” indicates a latch.
Technical Note
5/15
www.rohm.com 2010.10 - Rev.
A
© 2010 ROHM Co., Ltd. All rights reserved.
BD3870FS,BD3871FS,BD3872FS,BD3873FS
●Block diagram, application circuit, pin assig nme nt (BD3870FS, BD3871FS, BD3873FS )
Unit: Resistance =Ω, Capacitor = F
Fig.2
●Pin descriptio n (BD3870FS, BD3871FS, BD3873FS)
Pin No. Pin Name Description Pin No. Pin Name Description
1 VIN1 1ch volume input pin 13 SC Serial clock input pin
2 VIN2 2ch volume input pin 14 SI Serial data input pin
3 SEL2 2ch input selector output pi n 15 VCC Power supply pin
4 SEL1 1ch input selector output pin 16 OUT 2 2ch output pin
5 A1 1ch in put pin A 17 OUT1 1ch outp ut pin
6 A2 2ch in put pin A 18 BOUT1 1ch bass filter setting pin
7 B1 1ch in put pin B 19 BNF1 1ch bass filter setting pi n
8 B2 2ch in put pin B 20 BOUT2 2ch bass filter setting pin
9 C1 1ch input pi n C 21 BNF2 2ch bass filter setting pi n
10 C2 2ch input pin C 22 TNF2 2ch treble filter setting pin
11 FILTER 1/2 VCC pin 23 TNF1 1ch treble filter setting pin
12 GND Ground pin 24 CAP
T ime constant setting pin for absorbing
surround switching shock sou nd
5.6k
5.6k
Surround
13 1415161718192021 22 23 24
12 1110
9 8 7 6 5 4 3
2 1
Treble1
fc=8kHz Treble２
fc=8kHz Bass2
f0=80Hz Bass1
f0=80Hz
Logic
Vcc/2
Vcc/2 Vcc/2
Vcc/2
Vcc/2
0dB
～
-87dB
-∞
50k 50k 50k 50k 50k 50k
10μ
10μ
47μ
10μ
10μ 10μ 10μ
10μ 10μ
4.7k 4.7k
A1 A
2
B1 B
2
C1 C2
CLOCK
DATA
LAT CH
VCC
OUT2
OUT1
10μ 10μ
390k 390
k
0.1μ
0.1μ0.1μ 0.1μ
0.0022μ 0.0022μ 0.33μ
Technical Note
6/15
www.rohm.com 2010.10 - Rev.
A
© 2010 ROHM Co., Ltd. All rights reserved.
BD3870FS,BD3871FS,BD3872FS,BD3873FS
●Block diagram, application circuit, pin assig nme nt (BD3872FS)
Unit: Resistance =Ω, Capacitor = F
Fig.3 Application to Cinema Surround
E2
+
10μ
E1 D2D1C2C1
CLOCKDATA
LATC H
Vcc
OUT2 OUT1
0.0022μ
390K
+
4.7μ
+
4.7μ
0.1μ 0.1μ
5.6K 0.1μ0.1μ
5.6K
390K
1718 19 20 21222324252627 28
1615 14 13 12
0.0022μ
3 2 1
2930 31 32
1110
9 8
7
6 5 4
0.22μ 0.1μ
B2B1
A
2
A
1
0.1μ0.1μ0.1μ0.1μ0.1μ0.1μ0.1μ
0.1μ0.1μ
4.7k 4.7k
0.33μ
0.022μ 0.001μ 0.001μ
0.22μ
Treble1
fc=10kHz Tr eble2
fc=10kHz Bass1
f0=80Hz Bass2
f0=80Hz
Logic
Vcc/2 Vcc/2
100k 100k 100k 100k 100k 100k 100k 100k 100k 100k
Vcc/2
Vcc/2
Surround
Loud
speaker Loud speaker
equalizer2
0dB
～
-87dB
-∞
Vcc/2
0dB
～
-87dB
-∞
62K
Vcc/2 Vcc/2
Technical Note
7/15
www.rohm.com 2010.10 - Rev.
A
© 2010 ROHM Co., Ltd. All rights reserved.
BD3870FS,BD3871FS,BD3872FS,BD3873FS
Unit: Resistance =Ω, Capacitor = F
Fig.4 Application to Loud Speaker Equalizer
E2
+
10μ
E1D2D1C2C1
CLOCKDATA
LAT CH
Vcc OUT2 OUT1
0.0022μ
390K +
4.7μ
+
4.7μ
0.1μ0.1μ
5.6K 0.1μ0.1μ
5.6K
390K 1718 19 2021222324252627 28
1615 14 1312
0.0022μ
3 2 1
2930 31 32
1110
9 8
7
6 5 4
0.22μ 0.1μ
B2B1
A
2
A
1
0.1μ 0.1μ0.1μ0.1μ0.1μ0.1μ0.1μ
0.1μ0.1μ
4.7k 4.7k
0.33μ
0.01μ 0.33μ 0.01μ 0.33μ
0.22μ
Treble1
fc=10kHz Treble２
fc=10kHz Bass1
f0=80Hz Bass2
f0=80Hz Logic
Vcc/2 Vcc/2
100k 100k 100k 100k 100k 100k 100k 100k 100k 100k
Vcc/2
Vcc/2
Surround
Loud speaker
equalizer1 Loud speaker
equalizer2
0dB
～
-87dB
-∞
Vcc/2
0dB
～
-87dB
-∞
Technical Note
8/15
www.rohm.com 2010.10 - Rev.
A
© 2010 ROHM Co., Ltd. All rights reserved.
BD3870FS,BD3871FS,BD3872FS,BD3873FS
●Pin descriptio n (BD3872FS)
Pin No. Pin Name Description Pin No. Pin Name Description
1 VIN1 1ch volume input pin 17 SC Serial clock input pin
2 SEL1 1ch input selector output pi n 18 SI Serial data input pin
3 VIN2 2ch volume input pin 19 VCC Power supply pin
4 SEL2 2ch input selector output pin 20 CAP T ime constant setting pin for absorbing
switching shock sound
5 A1 1ch in put pin A 21 OUT2 2ch outp ut pin
6 A2 2ch in put pin A 22 OUT1 1ch outp ut pin
7 B1 1ch in put pin B 23 BOUT2 2ch bass filter setting pin
8 B2 2ch in put pin B 24 BNF2 2ch bass filter setting pi n
9 C1 1ch input pi n C 25 BOUT1 1ch bass filter setting pin
10 C2 2ch input pin C 26 BNF1 1ch bass filter setting pin
11 D1 1ch input pin D 27 TNF2 2ch treble filter setting pin
12 D2 2ch input pin D 28 TNF1 1ch treble filter setting pin
13 E1 1ch input pin E 29 SOUT2 2ch cin ema su rround or SEQ setting pin
14 E2 2ch input pin E 30 SQI2 2ch cinema surround or SEQ se tting pin
15 FILTER 1/2 VCC pin 31 SOUT1 1ch cinema surround or SEQ se t ting pi n
16 GND Ground pin 32 SQI1 1ch cinema surroun d or SEQ setting pin
Technical Note
9/15
www.rohm.com 2010.10 - Rev.
A
© 2010 ROHM Co., Ltd. All rights reserved.
BD3870FS,BD3871FS,BD3872FS,BD3873FS
C1 C2
R3 R4
IN
R1
+
-
R2
(Hz)
R4 R3R2
C1C2R4R3R1R2
2π
1
f0
C2C1R1
R4R3R2
R1R2R4C1C2
Q
(dB)
1
C1
C2
R4R3R2R1
R2R3
1
C1
C2
R4R3R2R1
R4R3R2
20logG(boost)
●Description of operations
1) Bass filter
Using external components, center frequencies and Q factors of the bass characteristics are flexible
Fig.5
Standard values of R3, R4 (reference)
(R1=5.6kΩ, R2=390kΩ, C1=C2= 0.1µF)
Bass Boost Cut Amount Resistance (kΩ) * Typ.
R3 R4
0dB 77.64 0
2dB 58.90 18.73
4dB 44.02 33.60
6dB 32.20 45.42
8dB 22.82 54.80
10dB 15.36 62.26
12dB 9.44 68.18
14dB 4.78 72.84
* The actual boost cut amount may deviate from the standard values in some degree.
ٛ(
ٛ
ٛٛ dB)
1
C1
C2
R4R3R2R1 R4R2(R3
1
C1
C2
R4R3R2R1 R2R3
20logcutG
Fig.6
G
f
F0
G
G
Technical Note
10/15
www.rohm.com 2010.10 - Rev.
A
© 2010 ROHM Co., Ltd. All rights reserved.
BD3870FS,BD3871FS,BD3872FS,BD3873FS
2) Treble filter
Fig.7
Standard values of R1, R2 (reference)
Treble Boost Cut Amount Resistance (kΩ) * Typ.
R1 R2
0dB 0 36.28
2dB 7.46 28.82
4dB 13.39 22.89
6dB 18.10 18.18
8dB 21.84 14.44
10dB 24.81 11.47
12dB 27.20 9.08
14dB (BD3872FS only) 29.04 7.24
* The actual boost cut amount may deviate from the standard values in some degree.
3) Matrix surround
Fig.9
Matrix surround is constructed as shown above. Gains are defined as follows:
In-phase Gain: Gains obtained on OUT1 and OUT2 against IN1 when inputting a signal of the equivalent level and
in-phase (L=R) to IN1 and IN2.
1LL
2
2.14
L
2
4.14
IN2
OUT2
IN1
OUT1
(dB) 020log1
Single-phase Gain: Gains ob tained on OUT1 and OUT2 against IN1 when inputting a signal to IN1 and AC-grounding IN2
(R=0).
2,07LL
2
4.14
IN1
OUT1
1.07LL
2
2.14
IN1
OUT2
(dB)6.320log2.07
(dB)
0.591.0720log
Opposite-phase Gain: Gains obtained on OUT 1 and OUT2 against IN1 when inputting signals of the equiv alent level and
opposite-phase (L-R) to IN1 and IN2.
fc = (Hz)
G (boost) = 20log (dB)
G (cut) = 20log (dB)
Zc = (Ω)
2πR2C
1
R2+Zc
R1+R2+Zc
R1+R2+Zc
R2+Zc
j
ωc
1
R2
IN
OUT
C
+
-
R1
+
+
-
×1/2
×1/2
+
L
R
IN1
IN2
+
-
×2.14
(4.14L/2- 2.14R/2)
OUT1
OUT2
(4.14R/2- 2.14L/2)
+
+
+
3.14LL
2
2.14
L
2
4.14
IN2
OUT2
IN1
OUT1
(dB)1020log3.14
Fig.8
G
f
fc
G
3dB
G
3dB
Technical Note
11/15
www.rohm.com 2010.10 - Rev.
A
© 2010 ROHM Co., Ltd. All rights reserved.
BD3870FS,BD3871FS,BD3872FS,BD3873FS
1) Sound generati on using Loud Speaker Equa lizer (BD3872FS)
Using external components, one of the following two functions can be established; one having an effect to localize the
vocal forward and enhance it (Loud Speaker Equalizer) and the other having an effect to clarify the vocal quality and
improve the Articulation Index (Cinema Surround). Those characteristic values can be adjusted by choosing the external
components with desirable constants. Details of above two functions are described below:
◎Cinema Surround
Constructing the external components as shown below allows the vocals to be moved forward and enhanced.
Surround effect with enhanced vocal is achiev ed by turning on the built-in surround simultaneously.
Merging this effect, while playing movies on a DVD player, will make vocal listening clearer and surround effect
more impactful.
Fig.10
◎Loud Speaker Equalizer (SEQ)
BOOM BOX and Micro-sound systems are often restricted to using small-diameter speakers because of location space.
These speakers, where the vocal range are attenuated, may give an impression of having a muffled vocal sound
with respect to its audibility. Using the Loud Speaker Equalizer, the vocal quality which degrades in small-diameter
speakers, can be improved and the Articulation Index is also increased.
Fig.11
・C1 can be selected to determine the frequency where the phase should be inverted.
C1 Frequency where the phase is inverted
Larger value Set to the lower frequency side
Smaller value Set to the higher frequency side
・C2 can be selected to determine the HPF cut-off frequency The SEQ gain remains constant.
1
fc = (Hz)
2RC
(Where R is a built-in resistance of 10kΩ)
Fig.12
32
Loud speaker
equalizer1 Loud speaker
equalizer2
31 30 29
HPF
C2 SOUT (29. 31pin)
Phase Shifter
C1 SEQ (30, 32pin)
IN OUT
GAIN
FREQUENCY
Fc
G=5dB
(Constant)
3dB
Technical Note
12/15
www.rohm.com 2010.10 - Rev.
A
© 2010 ROHM Co., Ltd. All rights reserved.
BD3870FS,BD3871FS,BD3872FS,BD3873FS
0
2
4
6
8
10
10 100 1000 10000 100000
FREQUENCY (Hz)
GAIN (dB)
0
2
4
6
8
10
0246810
VCC (V)
ICC (mA)
0.001
0.01
0.1
1
10
0.001 0.01 0.1 1 10
INPUT VOLTAGE (Vrms)
OUTPUT VOLTAGE (Vrms)
0.001
0.01
0.1
1
10
0.001 0.01 0.1 1 10
INPUT VOLTAGE (Vrms)
THD+N (%)
10
12
14
16
18
20
10 100 1000 10000 100000
FREQUENCY (Hz)
GAIN (dB)
0
5
10
15
20
25
30
10 100 1000 10000 100000
FREQUENCY (Hz)
GAIN (dB)
-15
-10
-5
0
5
10
15
10 100 1000 10000 100000
FREQUENCY (Hz)
GAIN (dB)
-15
-10
-5
0
5
10
15
10 100 1000 10000 100000
FREQUENCY (Hz)
GAIN (dB)
0
5
10
15
20
10 100 1000 10000 100000
FREQUENCY (Hz)
GAIN (dB)
-14～+14dB
2dB step
●Reference data
Fig.13 Circuit Current - Power Supply
Voltage Fig.14 Output Voltage - Input Voltage
(BD3870FS) Fig.15 Total Harmonic Distortion
ratio - Input Voltage (BD3870FS)
Fig.16 Current Gain - Frequen cy
(BD3870FS, BD3873FS)
Fig.17 Voltage Gain - Frequency
(BD3871FS) Fig.18 Bass Gain - Frequency
At 18dB setting At 24dB setting +14dB
-14～+14dB
2dB step
Fig.19 Treble Gain - Frequency
(BD3870FS,BD3871FS,BD3873FS) Fig.20 Treble Gain - Frequency
(BD3872FS) Fig.21 Surround Gain - Frequency
-15
-10
-5
0
5
10
15
10 100 1000 10000 100000
FREQUENCY (Hz)
GAIN (dB)
At oppoite-phase input
Fig. 22 Treble Gain - Frequen cy
(BD3872FS)
-14dB
+14dB
-14dB
+12dB
-12dB
-12～+12dB
2dB step
Technical Note
13/15
www.rohm.com 2010.10 - Rev.
A
© 2010 ROHM Co., Ltd. All rights reserved.
BD3870FS,BD3871FS,BD3872FS,BD3873FS
●Notes for use
1) Numbers and data in entries are representative design values and are not guaranteed values of the items.
2) Although ROHM is confident that the example application circuit reflects the best possible recommendations, be sure to
verify circuit characteristics for your particular application. Modification of constants for other externally connected circ uits
may cause variations in both static and transient characteristics for external components as well as this Rohm IC. Allow for
sufficient margins when determining circuit constants.
3) Absolute maximum ratings
Use of the IC in excess of absolute maximum ratings, such as the applied voltage or ope rating temperat ure range (Topr),
may result in IC damage. Assumptions should not be made regarding the state of the IC (short mode or open mode) when
such damage is suffered. A physical safety measure, such as a fuse, should be implem ented when using the IC at times
where the absolute maximum ratings may be exceeded.
4) GND potential
Ensure a minimum GND pin potential in all operating conditions. Make sure that no pins are at a voltage below the GND at
any time, regardless of whether it is a transient signal or not.
5) Thermal design
Perform thermal design, in which there are adequate margins, by taking into account the permissible dissipation (Pd) in
actual states of use.
6) Short circuit between terminals and errone ous mounting
Pay attention to the assembly direction of the ICs. Wrong mounting direct ion or shorts between terminals, GND, or other
components on the circuits, can damage the IC.
7) Operation in strong electromagnetic field
Using the ICs in a strong electromagnetic field can cause operation malfunction.
8) Power-ON RESET
A built-in circuit for performing initialization inside the IC at p ower-ON is provide d. In unstable systems it is recommende d
that the data shall be sent to all the addresses during power-ON, until this operation c ycle is completed . Mute should be
applied during this cycle.
Function Initial Condition
Input Selector Input A
Input Gain 0dB
Loud Speaker Equalizer (BD3872FS only) OFF
Volume -dB
Surround OFF
Treble Gain 0dB
Bass Gain 0dB
9) 2-wire serial control
For the CL and DA terminals, the patterned and other wirings should be routed as not to cause interference with the
analog-signal-related lines.
10) Switching between functions
Shock sound is absorbed when switching between the volume, bass, and treble functions.
11) Input coupling capacitor
As described in the figure bel ow, low frequency characteris t ics are determined depe nding on the e xternal capacitor value
for input coupling, and the input imped ance value inside the IC.
Fig.23 Fig.24
f
G
0
A (f)
C
R
A(f) = 1+(2πfCR)2
(2πfCR)2
Technical Note
14/15
www.rohm.com 2010.10 - Rev.
A
© 2010 ROHM Co., Ltd. All rights reserved.
BD3870FS,BD3871FS,BD3872FS,BD3873FS
12) Switching noise
For Surround and Loud Speaker Equalizer (BD3872FS only), external capacitor C is attached to the CAP pin as a measures
to control the switching noise. In the application circuit, a constant value as an example, is indicated by the CAP pin.
The time constant, which is used to charge/discharge the external capacitor C (var ying bet ween Vbe to 5Vbe (2.65V)) on
the CAP pin, controls the soft switching operation. The switching time constant T is stated as T=2.55×105×C.
Vbe has a temperature chara c teristic and may affect the time constant T.
13) Input Selector and Input Gain
When setting/changing Input Selector or Inp ut Gain, the soft switching operation does not function and therefore no ise is
not controlled. For this reason, it is recommended to provide a mute circuit constructed of the external components for the
set design.
MUTE setting example
Fig.25
●Thermal Derat in g Curve
Fig.26
When installed ROHM standard board
(70×70×1.6mm Glass epoxy board)
0
200
400
600
800
1000
1200
0 25 50 75 100 125
Ambient Temperature: Ta( ℃)
Power Dissipation : Pd （mW)
SSOP-A32
SSOP-A24
MUTE
(L=ON, H=OFF)
SERIAL DATA
INPUT SOURCE
SERIAL DATA
40～60ms 500～600ms
Technical Note
15/15
www.rohm.com 2010.10 - Rev.
A
© 2010 ROHM Co., Ltd. All rights reserved.
BD3870FS,BD3871FS,BD3872FS,BD3873FS
●Ordering part number
B D 3 8 7 0 F S - E 2
Part No. Part No.
3870,3871,3873
3872
Package
FS: SSOP-A24
SSOP-A32
Packaging and forming specification
E2: Embossed tape and reel
∗
Order quantity needs to be multiple of the minimum quantity.
<Tape and Reel information>
Embossed carrier tapeTape
Quantity
Direction
of feed
The direction is the 1pin of product is at the upper left when you hold
reel on the left hand and you pull out the tape on the right hand
2000pcs
E2
()
Direction of feed
Reel 1pin
(Unit : mm)
SSOP-A32
1
17
16
32
0.11
0.3MIN
0.36±0.1
0.8
13.6±0.2
0.15±0.1
5.4±0.2
7.8±0.3
1.8±0.1
(MAX 13.95 include BURR)
0.1
∗
Order quantity needs to be multiple of the minimum quantity.
<Tape and Reel information>
Embossed carrier tapeTape
Quantity
Direction
of feed
The direction is the 1pin of product is at the upper left when you hold
reel on the left hand and you pull out the tape on the right hand
2000pcs
E2
()
Direction of feed
Reel 1pin
(Unit : mm)
SSOP-A24
24
0.1±0.1
12
0.8
−4°
+6°
0.17−0.05
+0.1
13
1.8±0.1
4°
0.38±0.1
1
10±0.2
0.5±0.2
1.2±0.15
7.8±0.3
5.4±0.2
(MAX 10.35 include BURR)
0.1
Datasheet
Datasheet
Notice - GE Rev.002
© 2014 ROHM Co., Ltd. All rights reserved.
Notice
Precaution on using ROHM Products
1. Our Products are designed and manufactured for application in ordinary electronic equipments (such as AV equipment,
OA equipment, telecommunication equipment, home electronic appliances, amusement equipment, etc.). If you
intend to use our Products in devices requiring extremely high reliability (such as medical equipment (Note 1), transport
equipment, traffic equipment, aircraft/spacecraft, nuclear power controllers, fuel controllers, car equipment including car
accessories, safety devices, etc.) and whose malfunction or failure may cause loss of human life, bodily injury or
serious damage to property (“Specific Applications”), please consult with the ROHM sales representative in advance.
Unless otherwise agreed in writing by ROHM in advance, ROHM shall not be in any way responsible or liable for any
damages, expenses or losses incurred by you or third parties arising from the use of any ROHM’s Products for Specific
Applications.
(Note1) Medical Equipment Classification of the Specific Applications
JAPAN USA EU CHINA
CLASSⅢ CLASSⅢ CLASSⅡb CLASSⅢ
CLASSⅣ CLASSⅢ
2. ROHM designs and manufactures its Products subject to strict quality control system. However, semiconductor
products can fail or malfunction at a certain rate. Please be sure to implement, at your own responsibilities, adequate
safety measures including but not limited to fail-safe design against the physical injury, damage to any property, which
a failure or malfunction of our Products may cause. The following are examples of safety measures:
[a] Installation of protection circuits or other protective devices to improve system safety
[b] Installation of redundant circuits to reduce the impact of single or multiple circuit failure
3. Our Products are designed and manufactured for use under standard conditions and not under any special or
extraordinary environments or conditions, as exemplified below. Accordingly, ROHM shall not be in any way
responsible or liable for any damages, expenses or losses arising from the use of any ROHM’s Products under any
special or extraordinary environments or conditions. If you intend to use our Products under any special or
extraordinary environments or conditions (as exemplified below), your independent verification and confirmation of
product performance, reliability, etc, prior to use, must be necessary:
[a] Use of our Products in any types of liquid, including water, oils, chemicals, and organic solvents
[b] Use of our Products outdoors or in places where the Products are exposed to direct sunlight or dust
[c] Use of our Products in places where the Products are exposed to sea wind or corrosive gases, including Cl2,
H2S, NH3, SO2, and NO2
[d] Use of our Products in places where the Products are exposed to static electricity or electromagnetic waves
[e] Use of our Products in proximity to heat-producing components, plastic cords, or other flammable items
[f] Sealing or coating our Products with resin or other coating materials
[g] Use of our Products without cleaning residue of flux (even if you use no-clean type fluxes, cleaning residue of
flux is recommended); or Washing our Products by using water or water-soluble cleaning agents for cleaning
residue after soldering
[h] Use of the Products in places subject to dew condensation
4. The Products are not subject to radiation-proof design.
5. Please verify and confirm characteristics of the final or mounted products in using the Products.
6. In particular, if a transient load (a large amount of load applied in a short period of time, such as pulse. is applied,
confirmation of performance characteristics after on-board mounting is strongly recommended. Avoid applying power
exceeding normal rated power; exceeding the power rating under steady-state loading condition may negatively affect
product performance and reliability.
7. De-rate Power Dissipation (Pd) depending on Ambient temperature (Ta). When used in sealed area, confirm the actual
ambient temperature.
8. Confirm that operation temperature is within the specified range described in the product specification.
9. ROHM shall not be in any way responsible or liable for failure induced under deviant condition from what is defined in
this document.
Precaution for Mounting / Circuit board design
1. When a highly active halogenous (chlorine, bromine, etc.) flux is used, the residue of flux may negatively affect product
performance and reliability.
2. In principle, the reflow soldering method must be used; if flow soldering method is preferred, please consult with the
ROHM representative in advance.
For details, please refer to ROHM Mounting specification
Datasheet
Datasheet
Notice - GE Rev.002
© 2014 ROHM Co., Ltd. All rights reserved.
Precautions Regarding Application Examples and External Circuits
1. If change is made to the constant of an external circuit, please allow a sufficient margin considering variations of the
characteristics of the Products and external components, including transient characteristics, as well as static
characteristics.
2. You agree that application notes, reference designs, and associated data and information contained in this document
are presented only as guidance for Products use. Therefore, in case you use such information, you are solely
responsible for it and you must exercise your own independent verification and judgment in the use of such information
contained in this document. ROHM shall not be in any way responsible or liable for any damages, expenses or losses
incurred by you or third parties arising from the use of such information.
Precaution for Electrostatic
This Product is electrostatic sensitive product, which may be damaged due to electrostatic discharge. Please take proper
caution in your manufacturing process and storage so that voltage exceeding the Products maximum rating will not be
applied to Products. Please take special care under dry condition (e.g. Grounding of human body / equipment / solder iron,
isolation from charged objects, setting of Ionizer, friction prevention and temperature / humidity control).
Precaution for Storage / Transportation
1. Product performance and soldered connections may deteriorate if the Products are stored in the places where:
[a] the Products are exposed to sea winds or corrosive gases, including Cl2, H2S, NH3, SO2, and NO2
[b] the temperature or humidity exceeds those recommended by ROHM
[c] the Products are exposed to direct sunshine or condensation
[d] the Products are exposed to high Electrostatic
2. Even under ROHM recommended storage condition, solderability of products out of recommended storage time period
may be degraded. It is strongly recommended to confirm solderability before using Products of which storage time is
exceeding the recommended storage time period.
3. Store / transport cartons in the correct direction, which is indicated on a carton with a symbol. Otherwise bent leads
may occur due to excessive stress applied when dropping of a carton.
4. Use Products within the specified time after opening a humidity barrier bag. Baking is required before using Products of
which storage time is exceeding the recommended storage time period.
Precaution for Product Label
QR code printed on ROHM Products label is for ROHM’s internal use only.
Precaution for Disposition
When disposing Products please dispose them properly using an authorized industry waste company.
Precaution for Foreign Exchange and Foreign Trade act
Since our Products might fall under controlled goods prescribed by the applicable foreign exchange and foreign trade act,
please consult with ROHM representative in case of export.
Precaution Regarding Intellectual Property Rights
1. All information and data including but not limited to application example contained in this document is for reference
only. ROHM does not warrant that foregoing information or data will not infringe any intellectual property rights or any
other rights of any third party regarding such information or data. ROHM shall not be in any way responsible or liable
for infringement of any intellectual property rights or other damages arising from use of such information or data.:
2. No license, expressly or implied, is granted hereby under any intellectual property rights or other rights of ROHM or any
third parties with respect to the information contained in this document.
Other Precaution
1. This document may not be reprinted or reproduced, in whole or in part, without prior written consent of ROHM.
2. The Products may not be disassembled, converted, modified, reproduced or otherwise changed without prior written
consent of ROHM.
3. In no event shall you use in any way whatsoever the Products and the related technical information contained in the
Products or this document for any military purposes, including but not limited to, the development of mass-destruction
weapons.
4. The proper names of companies or products described in this document are trademarks or registered trademarks of
ROHM, its affiliated companies or third parties.
DatasheetDatasheet
Notice – WE Rev.001
© 2014 ROHM Co., Ltd. All rights reserved.
General Precaution
1. Before you use our Pro ducts, you are requested to care fully read this document and fully understand its contents.
ROHM shall n ot be in an y way responsible or liabl e for fa ilure, malfunction or acci dent arising from the use of a ny
ROHM’s Products against warning, caution or note contained in this document.
2. All information contained in this docume nt is current as of the issuing date and subj ect to change without any prior
notice. Before purchasing or using ROHM’s Products, please confirm the la test information with a ROHM sale s
representative.
3. The information contained in this doc ument is provi ded on an “as is” basis and ROHM does not warrant that all
information contained in this document is accurate an d/or error-free. ROHM shall not be in an y way responsible or
liable for an y damages, expenses or losses incurred b y you or third parties resulting from inaccuracy or errors of or
concerning such information.
